化工过程中真空系统的选型设计

阐述了化工过程中真空系统的选型设计与计算方法,并对真空泵选型设计提出一些建议。结合工程应用实例,验证了设计计算方法的可行性。     

Positioning of the reaction zone for gas–liquid reactions in catalytic membrane reactor by coupling results of mass transport and chemical reaction study

The location of the reaction zone in the catalytic membrane contactor was determined for two-phase reaction system. As a model reaction oxidation of formic acid by Pt catalyst deposited in the ceramic membrane filtration layer was used. It was determined from gas–liquid mass transport experiments that at gas side overpressures from 0.5 to 0.9 bar the liquid was displaced from membrane support layer and that the tortuosity factor of membrane filtration layer is 3.1. It was estimated on the basis of CO₂ fluxes that the reaction zone is close to gas–liquid interface and that the locus of the reaction zone matches with O₂ penetration depth calculated on the basis of formic acid disappearance rate. It was also shown that partition coefficient of formic acid in the membrane filtration layer is higher than 1, otherwise formic acid could not migrate to the reaction zone. Only a small fraction of the catalyst was involved in the reaction. The apparent activation energy was estimated to be around 44 kJ/mol.     

通过优化设计及工艺控制提高火管废热锅炉制造质量

针对硫磺制酸装置火管废热锅炉的特点,论述优化设计和工艺控制方法。详细介绍了所执行的各种设计标准、设备结构和施工方法。建议严格遵守压力容器标准、规范和施工工艺,以提高废热锅炉制造质量,保证硫磺制酸装置安全、稳定、高效运行。     

Study on the control of pore sizes of membranes using chemical methods: Part III. The performance of carbonates and bicarbonates in the membrane-making process by the chemical reaction

In this paper, polyvinylidene fluoride (PVDF)/polymethyl acrilate (PMMA)/cellulose acetate (CA) blend UF membranes were prepared by chemical reaction introduced phase-inversion method. The results of the experiment show that: (1) The membrane pore size distribution is more uniform due to the presence of carbonates or bicarbonates in the coagulation bath; (2) No more than the stoichiometric ratio amount of carbonates or bicarbonates in the coagulation bath can effectively improve the membrane pore size distribution and make the pore size of membrane more uniform; (3) The membrane prepared by carbonates solution as a working solution in coagulation bath possess superior performance than that by bicarbonates.